There are known gas taps, adapted mainly to a household gas cooker, which comprise a safety valve inserted into a body of the tap, a rotatory shaft and an ignition switch that is operated when the user turns the rotatory shaft in a specific direction to generate the ignition of the flame, whereas when the user turns the rotatory shaft in the opposite direction, the ignition is not generated.
U.S. Pat. No. 4,019,855 discloses a gas tap that comprises a rotatory shaft, a cam connected to the rotatory shaft, a plate-type ignition switch with a fixed first terminal and a second terminal that moves, driven by the cam, towards the first terminal to generate the ignition. The cam includes a radial first projection disposed centrally and delimited by two parallel ramps, and a second projection that is disposed adjacent to the first projection, with the result that when the gas tap is turned in a direction of ignition the second terminal is moved by means of the ramp of the cam until the second projection causes the second terminal to come into contact with the terminal. If the tap is turned in an opposite direction to the ignition, the second terminal is moved by means of the ramp of the cam, and does not encounter during its stroke any other projection that moves it towards the first terminal, as a result of which contact is not generated.